Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 281136 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 736 AM EDT Wed Sep 28 2016 .SYNOPSIS... A cold front approaching from the west will stall through mid- week before moving across the area Thursday into Friday. Dry high pressure will build into the area by the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 630 AM Wednesday...Todays highlight will be the potential for thunderstorms to reach strong to possibly isolated severe status from midday thru well into this evening. Highlighted this possibility in the Hazardous Weather Outlook. Instability across the area has been lacking the past few days which that will change. The expansive closed upper low will cut off and drop from the southern Great Lakes to the central Appalachians by early Thu. Flow aloft will become cyclonic with unidirectional SW winds along with increasing speeds with height. Closer to the coast, low level winds will be more southerly. PWs increase to around 1.75 inches along with an influx of widespread upper 60s to low 70s sfc dewpoints, further enabling instability. POPs will peak at 50 percent over land today into this evening, and again during the pre-dawn Thu hrs across the eastern FA and adjacent local Atlantic Waters. Embedded mid-level s/w trofs rotating thru will partially affect the fa, mainly later tonight as 1 moves from the base of the upper low from the Gulf of Mexico today to across the eastern portions of the FA late tonight. For max/min temps, once again from 1 to possibly 2 categories above the norm, especially night time lows. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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As of 345 AM Wednesday...Of the 2 days, Thu will be the wetter of the 2 and exhibit the higher POPs. The main feature will be the cutoff low making its furthest southern positioning across the Central Appalachians. Thursday will feature embedded and stronger mid-level s/w trofs rotating around this cutoff low. The 1 Thu morning moves NE of the FA with the eastern 1/3 to 1/2 seeing ongoing convection at the start of the day, moving out of the FA by late morning. The next s/w rotating around and closer to the cutoff low, will help push a dry slot across portions of the FA late Thu aftn and night. With it not entirely thru the FA, will keep a POP for the far eastern portions of the ILM CWA Thu night into Fri. Finally, the models indicate the dry slut will finally shunt the remaining moist air off the Carolina coasts by late Friday. Improving wx conditions across the FA during Fri into Fri night. Max/Min Temps, stayed closer to a consensus with a lean toward the MET mos guidance based on its decent performance the past couple days.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/...
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As of 3 AM Tuesday...Despite the fact that the long term begins with an impressively large cutoff to our west the weather will be pretty quiet. The reason for this is that we will be in the dry slot of the occluded surface low to our NW and the deep moisture will be off the coast. Sunday and Monday as the weakening front pushes through some of this moisture may get drawn back to the coast for some minor rain chances-all while temperatures remain close to their seasonable norms. The front washes out by Monday leaving behind a weak surface pattern while mid level heights build. There will still be no real forcing for precipitation and no low level thermal advection to change temperatures much from the values earlier in the period.
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&& .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
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As of 12Z...Patchy IFR cigs are W of KFLO while a small area of MVFR cigs is affecting KILM. Buffer soundings suggest little chance of sub-VFR at any terminal after 12Z. Will likely include MVFR cigs around 2k feet at KILM through 13Z, and will need to watch KFLO for the next hour or two. Despite ample lift this morning, hi-res progs and MOS guidance are not indicating much in the way of any precipitation at the coastal terminals. Will include VCSH at KFLO/KLBT by mid-morning where MOS guidance is indicating a higher chance of development. This afternoon the best chance of thunderstorms will be KFLO/KLBT. Have indicated VCTS but confidence is low. There is higher confidence of showers/VCTS at KFLO/KLBT in the evening. EXTENDED OUTLOOK...Scattered SHRA/TSRA through Thursday. A cold frontal passage late Wednesday into Thursday. Primarily VFR expected Friday through Sunday.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 630 AM Wednesday...Sfc pressure pattern and gradient will begin to reflect the input from the upper closed to cutoff low dropping to the Central Appalachians by late tonight. Southerly winds at 5 to 10 kt today will become SW 10 to 15 kt tonight. This reflection of the sfc cold front still hung up across the western portions of the Carolinas. Significant seas will run 2 to 4 ft, with the majority of the seas comprised by a 1 to 3 foot ese ground swell at 11 second periods. The 4 footers will primarily affect the waters from Cape Fear northward. Instability has been questionable across the FA the past few days. However, this will change. In addition, an embedded midlevel s/w trof will push from the Gulf of Mexico today, NE and across the area waters later tonight. Expect convection to be more isolated to widely scattered today becoming scattered to areas of pcpn later tonight. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 345 AM Wednesday...Sfc pressure pattern and a tightening- some of the gradient, will result in SW winds at 10 to around 15 kt thru this period. Significant seas will run 2 to 3 feet with 4 footers possible Wed and Thu when winds will be closer to 15 kt sustained due to the semi-tightened sfc pg. Wavewatch3 and local Swan keeps the ESE 11 second period ground swell affecting the local waters but with some degradation. Local wind driven waves at 4 to 6 seconds will become the more dominant feature of the significant seas by late Thu thru Friday. The sfc cold front will finally push to the Carolina coasts during Friday, and stalling just offshore the ILM Waters Friday night. The dry slot or tongue will push across the waters late Friday ending the threat for showers and thunderstorms. LONG TERM/SATURDAY THROUGH SUNDAY/... As of 3 AM Tuesday...A weakening cold front running parallel to the coast will only slightly shift through the period moving from just onshore to just offshore. It`s parent surface cyclone will be well occluded and thus deprived of its energy source and so the whole system will feature a baggy and poorly defined pressure pattern. This is good news for most mariners though as winds will be quite light and somewhat variable through the period. Seas will be slightly elevated above what such slack winds would otherwise support since spectral wave bulletins show a myriad of wave elements. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MBB NEAR TERM...DCH SHORT TERM...DCH LONG TERM...MBB AVIATION...MRR

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